WO1996020364A1

WO1996020364A1 - System for adjusting the tension of the contact part of a belt drive mechanism

Info

Publication number: WO1996020364A1
Application number: PCT/DE1995/001856
Authority: WO
Inventors: Lutz Reuschenbach; Karl-Heinz Senger; Joachim Luh; Johan Luyckx; Riné PELDERS
Original assignee: Robert Bosch Gmbh
Priority date: 1994-12-28
Filing date: 1995-12-23
Publication date: 1996-07-04
Also published as: EP0797742B1; EP0797742A1; KR987001071A; DE59505797D1; US6050913A; KR100362955B1; DE19548722A1; JPH10512654A

Abstract

The invention comprises a method for adjusting the tension of the contact part which yields greater precision in estimating the likely engine torque and thus a better apportionment of tension. For this purpose the engine control unit, which controls the internal combustion engine, gives signals that make it possible to estimate the engine torque precisely. In a first embodiment this signal can for example be an engine control-generated estimated value for the likely engine torque. In a second embodiment these signals can be the amount of the air mass drawn by the internal combustion engine, or a signal derived therefrom, and the angular ignition spacing of the internal combustion engine. With a more precise estimation of the engine torque the tension on the contact part can be reduced, resulting in improved efficiency of the drive mechanism.

Description

System for adjusting the tension of the belt part of a belt transmission

State of the art

The invention relates to a system for adjusting the tension of the belt part according to the preamble of claim 1.

Such a system, which is known, for example, from EP, A1, 0 451 887, is described in FIG. 1. This document also relates to the setting of the tension of a belt (1), generally a belt, in a continuously variable belt transmission (2), consisting of the belt (1), a drive pulley (3) and a driven pulley (4), which is driven by a motor (11).

To adjust the ratio of the continuously variable belt drive and the tension of the belt (1), the drive pulley (3) and driven pulley (4) each consist of an axially fixed (7) or (8) and an axially movable conical pulley (9) or . (10). The drive pulley (3) is also referred to as the primary pulley and the driven pulley (4) as the secondary pulley. The axially movable conical disks (9) or (10) are pressed against the belt means (1) by building up a hydraulic pressure in the oil chambers (5) or (6). By a suitable choice of the contact pressures Pp _r i and P _se ] _ζ in the oil chambers (5) and (6), the desired ratio of the continuously variable belt transmission and the required tension of the belt means (1) can be set. A torque converter (12) and a planetary gear set (13) with clutches for forward and reverse travel can be present, for example, for the power transmission from the motor (11) to the drive pulley (3). The motor (11) can also drive the pump (14) of the continuously variable belt transmission. A transmission control (18) contains the electrical and hydraulic components for controlling the continuously variable belt transmission. The transmission control (18) contains means for adjusting the pressure in the oil chamber (6) or in the oil chambers (5) and (6).

In one embodiment, the transmission controller (18) adjusts the tension of the belt (1) to the pressure ^p i ⁿ sec ^ ^he driven-side oil chamber (6).

The tension of the belt means (1) must be set so that the efficiency of the continuously variable belt transmission is at a maximum. On the one hand, it is to be prevented that the looping means (1) slips through too little tension, and on the other hand the tension of the looping means (1) should not be too high in order to avoid high losses in the continuously variable looping transmission. In order to be able to reconcile both requirements, the torque transmitted from the drive pulley (3) to the driven pulley (4) must be known as precisely as possible. The torque to be transmitted to the drive pulley (3) is mainly determined by the torque of the motor (11) and the torque amplification factor of the torque converter (12).

EP, A1,0 451 887 describes a method for setting the pressure ^p sec ^ ⁿ ^ ^er output-side oil chamber (6). With this The angle of rotation (o -, ^) of the throttle valve (15) of the engine (11) is detected using a sensor (16). Furthermore, the speed (N _mot ) of the motor (11), the speed (Np _r i _m ) of the primary disc (3) and the speed (N _se j _ζ ) of the secondary disc (4) with speed sensors (19), (20) and (21) measured and forwarded to the transmission control (18) as corresponding signals. The angular position (α Dk) of the throttle valve measured with the sensor (16), the engine speed (N _mot ), the primary speed (p _r i _m ) and the secondary speed (N _se jς) are in the transmission control (18) used to adjust the tension of the looping means (1) by adjusting the pressure in the oil chamber (6).

To set the tension of the belt means (1), the engine torque to be expected is estimated using a map from the throttle valve angle and the engine speed. The engine torque to be expected is converted into an expected primary torque using the quotient formed from the primary speed and the engine speed in a map. The required pressure P _se k i- ⁿ ^ er output-side oil chamber for setting the tension of the belt element (1) is then calculated.

The disadvantage of using the throttle valve angle (OC _Q ^) to estimate the engine torque is that the throttle valve potentiometer must be adjusted very precisely. Even a small deviation of the measured throttle valve angle from the actual throttle valve angle can lead to a considerable deviation between the expected engine torque and the actual engine torque in the above method. Since it is difficult to guarantee that the throttle valve angle is always measured correctly, the belt tension must be kept above the required level with a higher safety reserve by setting a pressure which is higher by the reserve pressure in the oil chamber on the output side. That leads to higher ones Losses in the gearbox and in the pump. In addition, problems can arise when estimating the engine torque during dynamic driving conditions with major changes in the engine speed over time.

The object of the present invention is to optimize the adaptation of the belt tension to the actual motor torque.

This object is solved by the features of claim 1.

Advantages of the invention

As already mentioned, the invention is based on a system for adjusting the tension of the belt part of a belt transmission, which is preferably infinitely variable in its translation. The voltage is set depending on the operating parameters of the vehicle engine. The essence of the invention is that a signal representing the engine torque is used as the operating parameter of the vehicle engine. This has the advantage that the belt tension can be better adapted to the actual engine torque than when using the throttle valve signal.

In an advantageous embodiment of the invention, it is provided that a signal representing the stationary engine torque is used as the operating parameter of the vehicle engine. This is to be understood as the engine torque to be expected at an engine speed which is essentially constant over time. This configuration has the advantage that this variable is relatively easy to determine and is generally present in an engine control unit.

It is particularly advantageous that the operating parameter of the vehicle engine is one that represents the dynamic engine torque Signal is used. As a result, the belt tension is optimally adjusted even during very dynamic driving conditions in which the engine speed changes relatively strongly over time.

To obtain the dynamic engine torque, it can be provided that a signal representing the speed of the vehicle engine is detected and the signal representing the dynamic engine torque is determined taking into account the change over time of the signal representing the speed of the vehicle engine. In addition, a variable representing the inertia of the vehicle engine can be taken into account to determine the signal representing the dynamic engine torque.

In general, first means (engine control device) for controlling or regulating the vehicle engine and second means (transmission control device) for controlling or regulating the belt transmission are provided. It is then particularly advantageous that the signal, which represents the engine torque, is formed in the first means and is fed to the second means for adjusting the voltage. Since a variable representing the engine torque is generally present in the engine control unit, this variant has the advantage that this variable can be supplied to the transmission control unit, for example via a torque interface (for example via a known bus system).

As an alternative to this, it can be provided that a first signal is transmitted from the first means (engine control) to the second means (transmission control), which represents the air mass or air quantity supplied to the vehicle engine. The signal representing the engine torque is then derived from this first signal. In addition, it can be provided that from the first means (engine control) to the second means (transmission control) in addition to the first signal (air mass or air volume), a second signal is carried, which represents the ignition angle or the ignition timing of the vehicle engine. The signal representing the motor torque for setting the voltage is then derived from the first and second signals.

While the last-mentioned variants relate to the determination of the actually expected engine torque in gasoline engines, it can be provided, for example in diesel engines, that a first signal is sent from the engine control unit to the transmission control unit, which represents the amount of fuel supplied to the vehicle engine. The signal representing the motor torque for setting the voltage is then derived from this first signal. In addition, it can be provided that a second signal is sent from the engine control unit to the transmission control unit, which represents the point in time at which the fuel is injected. The signal representing the motor torque for setting the voltage is then derived from the first and second signals.

The belt part is tensioned by pressurizing at least one pressure chamber.

In summary, it can be said that the invention includes a method for adjusting the tension of the belt means, in which a higher accuracy of the estimation of the expected engine torque and thus a better dosage of the tension is achieved. For this purpose, signals are made available by the engine control unit, which controls the internal combustion engine, which enable an exact estimation of the engine torque. In a first embodiment, this signal can be, for example, an estimated value for the expected engine torque, which is formed in the engine control. In a second embodiment, these signals can be the amount of the air mass drawn in by the internal combustion engine (or the amount of fuel supplied to the engine), or a signal derived therefrom, and the ignition angle of the internal combustion engine (or the time of injection). By more precisely estimating the engine torque, the tension of the belt means can be reduced, so that there is an improved transmission efficiency.

Further advantageous refinements can be found in the subclaims.

drawing

1 and 3 show the prior art as a block diagram, while FIGS. 2, 4a, 4b, 5a, 5b and 6 disclose block diagrams of the invention.

Embodiment

The invention is to be illustrated below with the aid of various exemplary embodiments.

2 shows an overview block diagram, the blocks already described with reference to FIG. 1 being given the same reference numerals.

FIG. 2 shows a continuously variable belt transmission with the transmission control (18) which is connected via the coupling (23) to the engine control (22) which controls the internal combustion engine (11). Compared to FIG. 1, there is a coupling (23) of engine control (22) and transmission control (18) with which one or more signals can be transmitted from engine control (22) to transmission control (18).

To control the motor (11), the motor control (22) receives various signals via the connections 116, 119 and 124 about the operating state of the motor. Via connections 125 and 130 actuators of the motor are controlled. This will be discussed in more detail with reference to FIG. 3.

Figure 3 shows a possible embodiment of the detection of signals (119), (124) and (116) and the control of the internal combustion engine (11) with the signals (125) and (130). A cylinder of the internal combustion engine (11) is shown. The signal (119), the speed N _{mot of} the engine, is measured with the speed sensor (19). The mass QL of the air (26) sucked into the intake manifold (29) is measured by a sensor (24) (air mass meter) and passed on as a signal (124) to the engine control (22). The motor control (22) actuates a device (25) for metering the fuel (27) with the signal (125). This can, for example, be injected into the suction pipe (29). The device (25) can be, for example, a fuel injection valve. Furthermore, from the engine control unit (22), the signal (130) is used to control α _{z of} the spark plugs (30) to ignite the fuel-air mixture in the interior of the combustion chamber (31) of the internal combustion engine (11).

The engine control (22) provides, among other things, signals (125) and (130) for controlling the internal combustion engine (11), which is dependent, among other things, on the signal (124) which indicates the mass of the air drawn in by the internal combustion engine (11). With a signal (119) the speed N _morj; of the internal combustion engine and with the signal (116) the angular position α ^ of the throttle valve to the engine control (22).

In a first embodiment of the invention, the engine control (22) determines the expected stationary engine torque ^M mot, stat ^and transmits the result as a signal (123a) via the coupling (23) to the transmission control (18). Methods for calculating the expected torque from the signals (119, N _mot ), (124, intake air Q ^), (116, α ^), (125, injection quantity) and (130, ignition timing α _z ) correspond to this State of the art like him DE-OS 42 39 711 can be seen. Furthermore, the engine speed N _mot can be fed to the transmission control (18).

In a second embodiment of the invention, the engine controller transmits a load signal (123b, Q__) formed from the signal (124, intake air QL) and the engine speed signal N _mot (119) by dividing (124, Q _L ) by (119, N _mot ) / ^N mot) ^{an d: Le} transmission control (18). Furthermore, the ignition timing α _z is also transmitted as a signal (123c) from the engine control (22) via the coupling (23) to the transmission control (18).

In both embodiments, the engine speed (119, N _mot ) and the angular position (116, α ^ k) of ^the throttle valve (15) can also be transmitted from the engine control (22) to the transmission control (18) via the coupling (23).

FIG. 4a shows the part of the transmission control (18) which is relevant for the second embodiment of the invention. As already mentioned, the transmission control (18) is supplied with the expected motor torque M _{mot s} tat -l ^s Sign l (123a) and the engine speed N _mot as signal 119 by the motor control (22) via the coupling (23). The stationary engine torque M _{mot s} at ^{w: Lr} d is either supplied to block 151 'or directly (bypassing block 151' shown in FIG. 4a) to block (150).

The variant in which the block (151 ') is provided is described below. In this variant, it is taken into account that the engine torque ^M mot stat formed in the engine control (22) corresponds to ^the instantaneous stationary engine torque, that is to say the engine torque at an essentially constant engine speed. In order to obtain the "dynamic" engine torque, the engine speed N _mot is first differentiated in time in block (1516 ') from the change in time N _mo t of the engine speed, the engine speed gradient. In block (1517 ') the inertia of the Motors (11) considered. This can, for example Schehen ge by the engine speed gradient N _mo t ^w ith a typical for the respective motor (11) inertia value I _mo t is multipli¬ sheet. The size thus obtained (N _mot * I _m OT) is superimposed to _mot the engine torque M which statio¬ ary engine torque M stat _mo t i ^m block (1515 ').

The engine torque M _mot (or, depending on the variant, the stationary engine torque _{mot (S} at) is fed to block (150). In block (150), depending on the (stationary) engine torque M _mα ( ^M mot, stat>' ^the primary speed N _pr i _m (speed sensor 20) and the secondary speed N _se ] _ζ (speed sensor 21) the setpoint pressure ° _k for the secondary side (oil chamber 6) .. The setting of the desired output-side oil pressure with electrical and hydraulic means can, for example, after mentioned EP, A1.0 451 887 take place.

FIG. 4b shows the part of the transmission control (18) that is relevant for the second embodiment of the invention. As already mentioned, the transmission control (18) via the coupling (23) from the engine control (22) receives the load signal (123b, Q _L / N _mo ), the ignition timing α _z as a signal (123c) and the current engine speed (signal 119, N _mot ). Depending on these signals in the block (151), depending on the embodiment, the stationary engine torque M _mot stat ° ^of the dynamic engine torque M _mot is formed as a signal 123a and supplied to the block (150). At block (150) is then mot dependent on the steady-state engine torque ^M, ^the primary revolution speed Np _r j_ _m (rotational speed sensor 20) and the secondary rotational speed N _s] _ζ (rotational speed sensor 21), the target pressure f ° _ι stat '7 (for the secondary side oil chamber 6 ) educated. The desired output-side oil pressure can be set by electrical and hydraulic means, for example according to EP, A1.0 451 887 mentioned at the beginning. The more detailed configuration of the block (151) is described with reference to FIG. 5a. For this purpose, FIG. 5 first shows the block torque calculation (1512) for calculating the expected stationary engine torque (M _mot stat 'signal 123a). The signal (1513) is calculated from the load signal (Q] _ / ^N mot 'signal 123b) and the engine speed (N _mot , signal 119) using block (1512), which contains a map calculation. In a second block (1514) the expected stationary engine torque ( ^M mot, stat 'signal 123a) is calculated from the signal (1513) and the ignition point (α _z , signal 123c).

A variant of the block (151) is shown in FIG. 5b. This variant takes into account that the engine torque M _mo t stat formed in blocks (1512) and (1514) corresponds to ^the instantaneous stationary engine torque, that is to say the engine torque when the instantaneous engine speed is kept constant. In order to obtain the "dynamic" engine torque, the engine speed N _mot is first differentiated in time in block (1516) from the time change N _{mot of} the engine speed, the engine speed gradient. In block (1517) the inertia of the motor (11) is taken into account. This can for example be done by the gradient of the engine speed N _m ot is connected to a respective for the motor (11) typi¬'s inertia value I _mo t multiplied. The variable ( _mo * I _mo t) thus obtained is superimposed on the stationary engine torque M _mot stat i ™ block (1515) to the engine torque M _mot .

The detailed design of the block (150, belt tension regulator) is described with reference to FIG. 6. 6 shows a block diagram for calculating the required pressure p S6fJK. in the

Oil chamber (6) for adjusting the tension of the belt means (1) in the first and second embodiment of the invention. With the block (15006), the signal Np _r i _m / N _{mot is formed} as a quotient of the primary speed N _pr i _m and the engine speed N _mot . The signal p i _r _m / N _mot and the estimated engine torque M _mot is converted in the block (15005) by a map calculation in the expected primary torque Mp _r i _m. In block (15007), the speed ratio i _{u of} the continuously variable belt transmission is calculated as the quotient of the primary speed Np _r i _m and the secondary speed N _gg ^ zu iü ^{= N} prim / ^N sek. In the block (15008) is a map of the expected primary torque p _r i _m and the speed ratio i _u, a minimum target pressure P _m i _{n is} calculated. To the minimum target pressure P _m i _n a reserve pressure P _r is added in the block (15009). The resulting signal P _res is filtered in block (15010) with a special low pass. However, the filter only works if the signal P _res becomes smaller. If the signal P _res becomes larger, then the output signal P ^ ^{1 of} the low-pass filter (15010) immediately follows the signal P _re s-

In block (15012), a centrifugal pressure P _{z is} calculated from the secondary speed Ng _g ^ with a map. This centrifugal contact pressure P _z is subtracted from the signal p ^tllt in block (15011). The difference ΔP is limited in block (15013) to minimum and maximum values. As a result, the required pressure in the oil chamber (6) is obtained with the signal P ° _k .

Claims

Expectations

1. System for adjusting the tension of the belt part (1) of a belt transmission, which is preferably infinitely variable in its translation, downstream of a vehicle engine (11), the tension being set as a function of operating parameters of the vehicle engine (11), thereby ge indicates that a signal representing the engine torque (M _mot stat _' ^M mot') is used as the operating parameter of the vehicle engine (II).

2. System according to claim 1, characterized in that a signal representing the stationary engine torque (M _mot stat) is used as the operating parameter of the vehicle engine (11).

3. System according to claim 1, characterized in that a signal representing the dynamic engine torque (M _mot ) is used as the operating parameter of the vehicle engine (11).

4. System according to claim 3, characterized in that a signal representing the speed of the vehicle engine (11) (N _mo ) is detected and the signal representing the dynamic engine torque (M _mot ) taking into account the temporal change (N _mot ) of the speed of the vehicle engine representative signal is determined.

5. System according to claim 4, characterized in that for determining the signal representing the dynamic engine torque

(M _mot ) a variable (I _m ot) representing the inertia of the vehicle engine (11) is taken into account.

6. System according to claim 1, characterized in that first means (22) for controlling or regulating the vehicle engine (11) and second means (18) for controlling or regulating the belt transmission are provided and

- The signal representing the engine torque (M _mo stat ' ^M mot ^ is formed in the first means (22) for estimating the expected engine torque and is fed to the second means (18) for adjusting the voltage.

7. System according to claim 1, characterized in that first means (22) for controlling or regulating the vehicle engine (11) and second means (18) for controlling or regulating the belt transmission are provided and

from the first means (22) to the second means (18) a first signal (Q _j _,) is supplied, which represents the air mass or air quantity supplied to the vehicle engine (11) and from the first signal (QL) that Signal representing engine torque (Mmot, stat ' ^M mot ^ ^{2ur der} Setting the voltage is derived.

8. System according to claim 7, characterized in that

from the first means (22) to the second means (18) in addition to the first signal (Q _L ) a second signal (α _z ) is supplied, which represents the ignition angle or the ignition timing of the vehicle engine (11) and

the signal representing the motor torque for setting the voltage is derived from the first and second signals.

9. System according to claim 1, characterized in that first means (22) for controlling or regulating the vehicle engine (11) and second means (18) for controlling or regulating the belt transmission are provided and

a first signal is supplied from the first means (22) to the second means (18), which represents the amount of fuel supplied to the vehicle engine, and

the signal representing the engine torque for setting the voltage is derived from the first signal.

10. System according to claim 9, characterized in that a second signal is supplied from the first means (22) to the second means (18) representing the point in time at which the fuel is injected, and -from the first and second signal, the signal representing the engine torque for setting the voltage is derived.

11. System according to claim 1, characterized in that the tension of the belt part (1) by means of a Druckbeauf¬ impacting at least one pressure chamber (5.6).